payment rate vs installment rate

payment rate and installment rate both are nouns.

Word	Noun	Adjective	Verb	Adverb
payment rate	Yes	No	No	No
installment rate	Yes	No	No	No

As nouns, payment rate and installment rate are synonyms defined as:

payment rate and installment rate: the amount of money paid out per unit time

Other synonyms of payment rate include rate of payment, repayment rate.

payment rate (noun)	installment rate (noun)
the amount of money paid out per unit time	the amount of money paid out per unit time